Tanning process.



ED STATES PATENT -FFICE.

SIGMOND SAXE, OF NEW YORK-N. Y.

TANNING PROCESS.

Specification of Letters Patent.

filed March 4, 1918. Serial No. 220.287.

To all whom it may concern:

Be it known that I, SIGMOND SAXE, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Tanning Processes;

and I do hereby declare the following to be volving drum with a much stronger vegetable tanning liquor comprising an extract of osage orange wood. The drum liquor may consist wholly of said extract or, more desirably, it may comprise a mixture or blend of said extract with one or more other vegetable tanning extracts.

The process of the present invention is concerned with the tanning of hides for' production of heavy leather, as distinguished from the tanning or tawing of skins for light leather. It is not concerned with chrome or other mineral tannages, nor

with the production of leather intended to be dyed, properly speaking. The process is especially important for the production of sole leather, and will therefore be explained hereinafter more particularly in that connection.

In making sole leather according to the usual practice heretofore prevail ng, the

hide is first partially tanned by soaking it in weak vegetable tan liquor, in a vat or pit until the hide is struck through. The partially tanned hide is then removed from the vat and placed in a revoluble drum with a strong vegetable tanning extract or mix ture of extracts, and the drum is revolved until the hide is completely tanned. It is generally recognized that the conditions under which the tanning reactions occur in the drum difler radically from those obtaining in vat or pit tanning.

I have found that a concentrated extract of the wood or bark of the osage orange or bois darc, herein termed broadly osage orange wood extract, is particularly efiecprotive for use in the second or drumming stage of heavy leather tanning. Aside from a limited use for fence posts and the like, osage orange wood has heretofore been practically a waste material without commercial application; but the present discovery of the special adaptability of its extract as a source of tanning material for tanning sole leather or other heavy leather in the drum not only renders this formerly practicallytworthless material highly-useful, but italso enables the tanner to produce better leather at less cost. Used alone, .osage orange wood extractherein described gives a tough strong leather; and when said extract is blended with other tanning extracts, which is most desirable in practice, it materially improves the leather obtainable by the use of such other extracts, in respect to strength, toughness and color. Examples of other tanning extracts suitable for blending with osage orange wood extract in practicing the present process are chestnut, quebracho, oak, hemlock, mangrove, cutch, etc. The term extract is here employed ,in its technical sense as understood in the trade, that is, as signifying a concentrated liquor or solid preparation rich in tanning values.

An osage orange wood extract suitable for use in carrying out my process may be pre pared by leaching the comminuted wood or bark, or both, of the osage orange, best with the aid of heat and superatmospheric pres sure, and then carefully concentrating the leachings by evaporation, under reduced pressure. The concentration of the finished extract may be varied as desired, but an extract having a specific gravity of about 51 Twaddell (or say 2930 Baum) is admirably suited for the purpose and serves as a convenient basis for computing proper proportions in blends with other extracts. A fair average sample of an osage orange wood extract of approximately this concentration, analyzed according to the oflicial method of the American Leather Chemists Association, shows the following:

Total solids 55.88% Total soluble solids 52.19% Insoluble material 3.69% Non-tannins 12.13% Tannin 40.06% Purity (percentagerelation of tannin to total so1ids 71.65%

Patented Mar. 11, 1919.v No Drawing. Continuation in part of application Serial No. 48,878, filed September 3, 1915. This application 

